The Great Saint Martin Church (Groß Sankt Martin) foundations (circa 960 AD) rest on remnants of a Roman chapel, built on what was then an island in the Rhine. The church was later transformed into a Benedictine monastery.
In 1150, a fire destroyed much of Cologne and it is supposed that the entire church was destroyed. The Archbishop of Cologne Philipp I. von Heinsberg sanctified the new building in 1172, and the first phase of construction, the tri-apsidal structure was built, with three round apses meeting in the shape of a cross. This is the only element of the church still present today. The eastern end of the nave was completed before a further fire in 1185, as well as aisles on the Southside. At the northern apse, two Benedictine chapels were later added, built over the ruins of the previous abbey buildings.
In the middle of the 13th century, new walls for the three apses were completed, with larger windows. These provided a sought-after lightness to the interior. The nave was also made five meters longer, and the atrium in the west was built.
After the completion of the church in the 13th century, few modifications to the form of the church were undertaken. Most significant during this period were the various renovations needed for the four surrounding towers.
Reforms under abbots Jakob von Wachendorp (1439–1454) and Adam Meyer (1454–1499) provided a stronger financial footing for the Benedictine abbey. From this the inner decoration of the church was embellished, including figures from the altar, installed in 1509, that are still present today.
In 1707, the decaying interior walls were repaired and refurbished. Heinrich Obladen, then the abbot of Great Saint Martin, also purchased a new, larger organ for the church. New adornments for the Church took on a Baroque style, including golden bands for the pillars, dome and walls.
The church was badly damaged in World War II; restoration work was completed in 1985.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.